This invention comprises an improvement on the injection devices disclosed in my prior U.S. Pat. Nos. 3,605,742 and 3,702,608.
Various forms of spring-equipped syringe holders and actuators have been heretofore provided. Some of these previous devices include structure by which an associated syringe may be projected in order to extend the needle portion thereof for penetration into adjacent skin tissue and additional structure whereby the plunger portion of the syringe may be advanced relative to the barrel portion thereof by spring pressure in order that the liquid contents of the syringe may be expressed from the needle portion thereof beneath the penetrated skin tissue. However, these previous devices have been at best awkward to operate in that they include variously remotely located trigger members for independently actuating the spring structure for projecting the syringe and the spring structure for subsequently advancing the plunger portion of the syringe relative to the barrel portion thereof.
Examples of previously patented devices of this type and other syringe holders including some of the basic structure of the instant invention are disclosed in U.S. Pat. Nos. 2,742,116, 2,605,766, 2,671,448, 2,752,918, 2,960,087 and 3,055,362.